Investigating Catchment Hydrology and Low Flow Characteristics using GIS

The most frequent use of Geographic Information Systems (GIS) in hydrology has been in input/output data handling for modeling purposes, as well as in the derivation of flow direction, flow length and slope maps from Digital Elevation Models (DEMs). In turn, these maps have been merged with other maps, such as soils, land use, and vegetation maps to obtain flow velocities, isochrones, and Hydrologic Response Units (HRUs). This study presents examples of GIS applications to 1) create a depression-less DEM from contour lines of terrain elevation 2) interpolate groundwater heads based on head measurements at geo-referenced points, 3) derive topographic catchments based on the DEM and derive groundwater contributing areas to given surface points based on interpolated head values, and 4) estimate streamflow characteristics based on topographic catchments, groundwater contributing areas, and soil maps. Our results indicate the usefulness of GIS applications in spatial hydrologic analysis, interpolation, and prediction.